Enhanced photocatalytic degradation of 4-chlorophenol by Zr4+ doped nano TiO2

Zr4+ doped nano titania was prepared by sol–gel method using titanium(IV) isopropoxide and zirconium nitrate as precursors. The materials were characterized by XRD, BET, UV–vis, FT-IR, SEM-EDX and TEM techniques. The nanoparticles of pure TiO2 contained both anatase and rutile phases together but Zr4+ doped TiO2 gave anatase phase only. The framework substitution of Zr4+ in TiO2 was established by XRD, SEM-EDX and FT-IR techniques. The band gap value of Zr4+ doped TiO2 was higher than the parent nano TiO2. TEM observations confirmed the nanocrystalline nature of Zr4+ doped TiO2. The presence of dopants therefore could suppress the growth of TiO2 grains, increase the surface area, decrease the anatase–rutile phase transformation and accelerate the surface hydroxylation. These properties resulted higher photocatalytic activity for Zr4+ doped nano TiO2 than undoped nano TiO2. The presence of anatase type structure in TiO2 with high crystallinity and high phase stability, even after annealing at 800 °C substantially indicated that the dopants might inhibit densification and crystallite growth by providing dissimilar boundaries. The photocatalytic activity in the degradation of 4-chlorophenol was found to be higher for Zr4+ doped TiO2 than both nano TiO2 and commercial TiO2 (Degussa P25). The experimental parameters such as initial concentration of 4-chlorophenol, catalyst loading, pH and light intensity were optimized for maximum degradation efficiency.

Graphical abstractPure and Zr4+ doped nano TiO2 was prepared by sol–gel method using titanium(IV) isopropoxide and zirconium nitrate as precursors. The photocatalytic degradation of 4-chlorophenol (4-CP) in aqueous solution was carried out using pure and Zr4+ doped TiO2. Experimental results revealed that 3 mol% Zr4+ doped TiO2 requires shorter irradiation time for complete mineralization of 4-CP than pure nano TiO2 and commercial TiO2 (Degussa P25). Figure optionsDownload full-size imageDownload as PowerPoint slide